Conventionally, a method is known in which a heavy-weight workpiece is gripped by a gripper of a balancer, and a robot grips the gripper of the balancer and moves the heavy-weight workpiece on a given conveyance route (e.g., see Patent Document 1).
In this method, a worker guides the gripper of the balancer to the heavy-weight workpiece which is placed at a given position, and makes the gripper to grip the heavy-weight workpiece. Then, the balancer is gripped by a gripper of the robot, and the gripper of the robot is moved to a conveyance position on the conveyance route. Thus, the heavy-weight workpiece is conveyable by the small-volume robot with a simple structure.